The optimal method of determining appropriate treatments is the randomized control trial (RCT), and we are involved in a number of RCTs for patients with AIDS or related problems. However, for many reasons, definitive results may not be available for some Lime. There are a number of techniques which use information which is already available, or which can be estimated, to attempt to provide interim answers for those who must make decisions. we propose to apply these methods to the rapidly expanding literature reporting on clinical trials in AIDS and other HIV-related problems. One such method is meta-analysis, the science of critical evaluation and statistical combination of the results of individual studies. We have developed methods for assessing the technical quality of randomized control trials and guidelines for the conduct of meta-analysis. Decision analysis is a formal method of combining information to aid decision-makers in making the optimal choice when the costs, risks or benefits of two or more competing strategies uncertain. We have used this technique in several areas related to infectious diseases, and propose to apply decision analysis and cost effectiveness analysis to a number of controversies in the treatment of patients with AIDS and other HIV related problems. We also propose to explore methods for improving meta-analyses, and of combining expert opinions with other data to provide clearer answers to clinical dilemmas.